The Los Angeles Police Department are investigating the source of the ketamine which caused the tragic death of Matthew Perry.

The actor, best known for playing Chandler Bing in Friends, was found unresponsive in his swimming pool on October 28th, and was pronounced dead by paramedics at the scene.

A post-mortem later ruled his death as an accident from “the acute effects of ketamine”.

The Graham Norton Show – BBC

Six months after his tragic passing, the LAPD has confirmed they’re working with the Drug Enforcement Agency to investigate why the 54-year-old had so much ketamine in his system.

His official autopsy report stated that Matthew was “receiving ketamine infusion therapy for depression and anxiety” at the time of his death, with the most recent dose reportedly taken one and a half weeks before his passing.

However, the report continued: “The ketamine in his system at death could not be from that infusion therapy, since ketamine’s half-life is three-to-four hours, or less.”

The County of Los Angeles Department of Medical Examiner also confirmed contributing factors in his death included drowning, coronary artery disease and the effects of buprenorphine (used to treat opioid use disorder).

The report also noted that he was “reportedly clean for 19 months” prior to his death, according to a witness interviewed by detectives.

In his memoir Friends, Lovers and the Big Terrible Thing, Matthew opened up about his lengthy battle with addiction and revealed he almost died when he was 49 years old.

The Friends star spent weeks in a hospital fighting for his life after his colon burst from opioid overuse.

The actor revealed he spent two weeks in a coma and five months in the hospital and had to use a colostomy bag for nine months.

He said that when he was first admitted to the hospital, “the doctors told my family that I had a 2 percent chance to live. I was put on a thing called an ECMO machine, which does all the breathing for your heart and your lungs. And that’s called a Hail Mary. No one survives that.”

Matthew, who was just 24 when he was cast as Chandler Bing in Friends, recalled a terrifying time in his career that he was taking 55 pills a day.

He told PEOPLE: “I didn’t know how to stop. If the police came over to my house and said, ‘If you drink tonight, we’re going to take you to jail,’ I’d start packing. I couldn’t stop because the disease and the addiction is progressive. So it gets worse and worse as you grow older.”

The late 54-year-old had been to rehab 15 times, and had 14 surgeries on his stomach so far.

Matthew said fans who read his book would be “be surprised at how bad it got at certain times and how close to dying I came”.

He continued: “I say in the book that if I did die, it would shock people, but it wouldn’t surprise anybody. And that’s a very scary thing to be living with. So my hope is that people will relate to it, and know that this disease attacks everybody. It doesn’t matter if you’re successful or not successful, the disease doesn’t care.”

“I’m an extremely grateful guy. I’m grateful to be alive, that’s for sure. And that gives me the possibility to do anything.”

“What I’m most surprised with is my resilience. The way that I can bounce back from all of this torture and awfulness. Wanting to tell the story, even though it’s a little scary to tell all your secrets in a book, I didn’t leave anything out. Everything’s in there.”

The cast of Friends during HBO’s reunion special

At the time, Matthew added that his story is one “that’s filled with hope. Because here I am.”

The late 54-year-old rocketed to fame alongside Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer in Friends – which ran for 10 seasons from 1994 until 2004.

Matthew’s funeral was held at the Forest Lawn Church of the Hills in LA on November 3, where his co-stars were in attendance, as well as his close friends and family.

After the service, the late actor was laid to rest in the cemetery opposite the Warner Brothers Studios, where he filmed 10 seasons of the iconic US sitcom Friends.